Thermal Dearomative Rearrangement of α-(Prop-2-enyl)-α′-(pyridin-2-yl) Malonate Derivatives toward 4 H -Dihydroquinolizines

Reported herein is a thermally induced dearomative rearrangement of α-(aza-heteroaryl)-α'-prop-2-enyl malonate derivatives, affording 4H-dihydroquinolizine derivatives (21 examples, 26-89%). The rearrangement, assisted by microwave heating, afforded diastereoselective quinolizidine scaffolds, known for their broad biological activities. Experimental results and DFT calculations converge to support a stepwise mechanism initiated by intramolecular [1,4]-addition of pyridine nitrogen to the activated acrylate moiety followed by selective ester transfer.